1. Field
Example embodiments relate to a magnetic track and an information storage device. Other example embodiments relate to a magnetic track using magnetic domain wall movement and an information storage device including the same.
2. Description of the Related Art
Non-volatile information storing devices include a hard disc drive (HDD) and a random access memory (RAM). A conventional HDD may be a device for reading and writing information by floating a read/write head on a disk-shaped magnetic recording medium while rotating the magnetic recording medium. A conventional HDD also may be a nonvolatile information storage device that is capable of storing relatively large amounts of data, and may be used as a main storage device of a computer. However, the HDD may include a relatively large number of moving mechanical systems. When the HDD is moved or affected by shock, the systems may cause various mechanical troubles, and therefore the mobility and reliability of the HDD may be deteriorated. In addition, the mechanical systems may increase electrical power consumption and manufacturing cost of the HDD, and may cause various noises.
An example of a conventional flash memory is a non-volatile RAM. However, flash memory may have relatively slow reading and writing speeds and a relatively short life span. Memory devices, e.g., ferroelectric random access memory (FRAM), magnetic random access memory (MRAM), and phase change random access memory (PRAM), have been developed. However, because the flash memory, FRAM, MRAM, and PRAM all include a switching device in each memory cell, the memory cell area is difficult to reduce. Also, these memories have relatively small storage capacities when compared to a HDD.
Therefore, as a method of solving the drawbacks of the conventional non-volatile information storing devices as described above, storage devices have been developed, which are capable of storing relatively large amounts of data while not including moving mechanical systems and a relatively great number of switching devices. An example of this storage device is an information storage device using magnetic domain wall movement.
Magnetic fine regions constituting a magnetic material may be called magnetic domains. Directions of magnetic moments in a magnetic domain are the same. A magnetic domain wall may be a boundary region of magnetic domains having different magnetization directions from each other, and may have a predetermined or given volume. Such magnetic domains and magnetic domain walls may be moved in a magnetic material by a current or magnetic field applied to the magnetic material. When using the principle of magnetic domain and magnetic domain wall movement, an information storage device being capable of reading/writing data without mechanical movement of a recording medium and a read/write head may be realized.
One example of an information storage device to which principle of magnetic domain wall movement is applied is disclosed in the conventional art. The conventional information storage device may have a U-shaped magnetic track that is perpendicular to a substrate. The magnetic track may include a storage track and a buffer track having a length similar to the length of the storage track, and the buffer track may be any one of two pillar portions of the magnetic track. A plurality of magnetic domains may be continuously arrayed in the storage track, and magnetic domain walls may exist between the magnetic domains. A write head and a read head may be provided below the middle portion of the magnetic track. While moving the magnetic domains and the magnetic domain walls, writing or reading may be performed with the write head or the read head.
However, the magnetic track of the conventional storage device may be formed of a soft magnetic material, e.g., NiFe, having horizontal magnetic anisotropy, and a width of a magnetic domain wall existing in such a soft magnetic material may be as large as several hundred nanometers (nm). Therefore, recording density of the conventional storage device may be difficult to enhance. In addition, because movement of the magnetic domain wall in a soft magnetic material requires a relatively large current of about 108 A/m2, electric power consumption of the conventional storage device may be increased. Additionally, because it is difficult to make the height of the U-shaped magnetic track higher than about 20 μm (the height may be about 10 μm according to the size of a hole in which the U-shaped magnetic track is formed) with present etching and deposition technology, a marked increase of the storage capacity of the conventional storage device may be difficult.